Primary Frequency Standards at NIST
Abstract
NIST has a more than 50-year history of developing ever more accurate atomic frequency standards. For most of that time, the technology was based on thermal atomic beams of cesium atoms, and the accuracy improvement was approximately a factor of 10 every 7 years. To put this into some kind of perspective, both the period of this history and the rate of improvement are almost identical to the development of information-storage density in magnetic media. Now, however, with the advent of laser-cooling schemes and optical-frequency metrology, the rate of progress is dramatically increasing. This paper discusses briefly the last of the thermal-beam standards and our first laser-cooled, atomic-fountain standard. It then goes into some detail about the newly developed all-optical standards that use an optical-frequency transition in a single, laser-cooled, trapped mercury ion or in an ensemble of laser-cooled and trapped calcium atoms. Based largely on the increased operating frequency of the "clock" transition, these new standards have the potential for several orders of magnitude improvement in stability and, in the case of the mercury standard, accuracy over today's standards operating in the microwave region.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2001
- Accession Number
- ADA485638
Entities
People
- Robert Drullinger
Organizations
- National Institute of Standards and Technology